Link Fragment Interleaving (LFI) is a well known technology that is widely used in packet network routers. LFI is used to reduce delay and jitter by fragmenting large frames and prioritizing small frames.
The manner that LFI interleaves packets is illustrated in FIG. 1A. FIG. 1A shown a stream of interleaved packets. One stream of packets consists of packets A1, A2, and A3. A second stream of packets includes packets B1, B2 and B3. If packet B1 is transmitted after the transmission of packet A1, the delay would be too large.
Packet A1 is therefore broken into five segments A1a, A1b, A1c, A1d and A1e. Packets A2 and A3 are likewise broken into segments. Packet B1 is transmitted after segment A1a as shown in FIG. 1B. The other segments are also interleaved as shown. Existing commercially available network routers implement LFI to reduce delay and jitter in high priority data streams.
A Point-to-Point Protocol (PPP) is defined in the publicly available document entitled “RFC1661”. PPP is a widely used protocol that provides a set of rules for exchanging packets over a network. PPP provides a more stable transmission mechanism than that provided by older protocols. PPP also provides error checking features.
Multilink PPP (MLPPP) is a protocol that is defined in the publicly available document entailed “RFC1990”. MLPPP is a method of splitting, recombining, and sequencing packets across multiple logical data links. MLPPP is widely used in commercially available data routers. MLPPP provides a technique for multilink encapsulating and fragmenting packets to reduce delay. It is noted that real time packets are not encapsulated. Instead, real time packets are sent as raw PPP packets. The real time packets are interleaved between fragments as shown in FIG. 1B.
Present MLPPP devices, queue low priority packets prior to fragmentation as shown in FIG. 2. The queuing 201 can for example be based upon packet class specifications. As illustrated in FIG. 2, high priority packets are queued separately and they by-pass the fragmentation mechanism 202. After fragmentation the packets are encapsulated with a PPP header at 203 and passed to FIFO buffer 204 for subsequent transmission.